Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
4 · Fuerte
Límite del bosque
4 · Fuerte
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You could encounter very dangerous avalanches conditions Monday in places where heavy precipitation and warming temperatures tip the scale and cause natural avalanches. Stay away from areas where avalanches may start, run, and stop. With so much recent snow, any avalanche could grow large and deadly.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    2

    Yet another winter storm will impact the West-South zone Monday. Unlike recent systems, this storm should peak during the morning to mid-day hours with warming temperatures, heavy precipitation, and strong winds and could cause a natural avalanche cycle. Natural avalanches will be most likely in locations with the heaviest precipitation and windiest conditions such as near the volcanoes. If you travel to mid and upper elevations, stay away from areas where avalanches may start, run, and stop. With so much recent snow, any avalanche may grow large and become destructive. 

    Even if you don’t see natural avalanches where you travel, the up-side-down nature of this storm could create new storm slabs that you can trigger on any slope greater than 35 degrees. You can use small slope tests and hand-pits to look for weak layers in the new snow. You’re most likely to trigger storm snow layers above the New Years Day crust.

    (1/3/2021) Up track tests like this can highlight weak layers in the new snow. However, the only work as deep as your skis, snowshoes, or machine sinks into the snow. other weak layers could hide deeper.

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    On Sunday 1-2 feet of new snow fell at lower elevations. Now, with warming temperatures, this dry snow could see rain. Expect wet avalanches below the rain-snow line Monday. New rollerballs and tear-drop shaped slides should serve as clues for you that wet avalanches may occur. When you see these observations, steer around similar terrain. With so much recent snow, these slides could grow large and travel longer distances.

    (1/1/2021) New rollerballs on the Valley Rd near Paradise, Mt Rainier National Park. Clues like this indicate the surface snow is becoming wet and unstable.

Avalanche Discussion

The ongoing storm cycle continues to favor the volcanoes with the highest snow totals and likely greatest avalanche hazard in these locations. However, all areas in the West South zone have received notable precipitation since 12/29 (Paradise 7.46”, Crystal 2.79”, White Pass 3.57” as of Sunday afternoon). This caused the snowpack to increase by 2-4 feet at these same trailheads. And, this cycle isn’t over. 

As snow totals continue to grow so does our uncertainty. Several notable layers exist in the upper snowpack. On New Years Day, a thin rain crust formed and was buried in most locations. This layer served as the bed surface for several triggered avalanches by Crystal Mt Ski Patrol Sunday. Snowpack tests in the White Pass area also failed suddenly on this interface. On 12/29 a layer of surface hoar was buried and resulted in at least one avalanche around White Pass (E, 4300’). This layer can be tricky to locate, but it’s generally 6-10” above the very prominent 12/21 crust. With so much recent snow and so many potential layers, continue to exercise patience and allow the snowpack to adjust to the recent load. 

Over this stormy period, cornices grew large and overhanging on many ridgelines. Travelers on Sunday could trigger these waves of snow. Give this tricky mountain hazard plenty of space. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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